Reaction injection molded elastomers

ABSTRACT

This invention relates to reaction injection molded elastomers derived from high molecular weight amine terminated polyethers and/or high molecular weight polyols, a chain extender, a polyisocyanate, a chloro and/or isocyanate silane coupling agent, and untreated filler material. The reaction injection molded (RIM) elastomers of this invention are useful, for example, as automobile body parts.

This application is related to application Ser. No. 503,382, filed June8, 1983, now allowed. Also related are the following applications filedof even date: Ser. No. 645,721 and Ser. No. 645,600.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention concerns the field of reaction injection moldedelastomers.

2. Description of the Prior Art

U.S. Pat. Nos. 4,254,069 and 4,272,618 concern the curing of RIMpolyurethane elastomers. In the Glossary of these patents, a "polyol" isdefined as a di- or greater functionality high molecular weight alcoholor an amine terminated molecule composed of ether groups. In thediscussion of chain extenders in these patents, amines, includingaromatic diamines, are disclosed. However, the actual examples are ofpolyether polyurethanes using polyols (hydroxyl terminated) of highmolecular weight. The chain extender, monoethanolamine, was used as acrosslinker.

U.S. Pat. Nos. 3,838,076 and 3,847,992 disclose foams made from amineterminated polyethers, wherein the amine termination ranges from 10 to50 percent and 15 to 55 percent, respectively.

Quillery's U.S. Pat. No. 3,523,918 describes the use of amine chainextenders for the preparation of integral skin foams. Also, Weber's etal. U.S. Pat. No. 4,218,543 describes the use of high molecular weightpolyols, certain aromatic diamines and isocyanates for the production ofRIM parts. This patent assigned to Bayer specifically claims as a chainextender 1-methyl-3,5-diethyl-2,4-diaminobenzene (diethyltoluenediamine) and its isomer.

Turner's U.S. Pat. No. 4,246,363 claims a RIM polyurethane compositionderived from using at least three different polyols (including amineterminated polyethers) having specific relationships and reactivity andsolubility parameters to one another. Also, Vanderhider's U.S. Pat. No.4,269,945 claims a process for preparing RIM polyurethanes wherein arelatively high molecular weight hydroxyl containing polyol, a chainextender and a polyisocyanate are used. The chain extender may be analiphatic amine containing material having at least one primary aminegroup.

Previously filed applications, Ser. No. 371,377 and U.S. Pat. Nos.4,396,729; 4,444,910, and 4,433,067 relate to elastomers prepared usinga high molecular weight amine terminated polyether, an aromatic diaminechain extender and a polyisocyanate which may be merely a polyisocyanateor a quasi-prepolymer prepared from a polyol reacted with apolyisocyanate wherein isocyanate groups are still left unreacted.

The paper "Silane Effects and Machine Processing in Reinforced HighModulus RIM Urethane Composites," by E. G. Schwartz, et al., Journal ofElastomers and Plastics, volume 11 (October 1979), page 280, describesthe use of silane treated milled glass fibers in reinforced RIMcomposites.

The article "Surface Modification for RRIM Urethanes," by Ed Galli,Plastics Compounding, (January/February 1982) discloses silane treatedglass fiber reinforcement of RRIM urethanes. The emphasis is on aminosilanes.

The publication "Silane Coupling Agents," by Dow Corning Corporationdiscusses various silane coupling agents and their applications.

Application Ser. No. 502,382 filed June 8, 1983, discloses and claimsthe use of epoxy modified filler material in RIM elastomers made fromhigh molecular weight amine teminated polyethers and/or polyols.

Application Ser. No. 645,600 filed of even date related to epoxy silaneadded separately to a B-component containing filler material.

In conventional RIM systems, the so-called A-component contains theisocyanate, whether it is pure isocyante or a quasi-prepolymer, and aB-component which contains the active hydrogen containing materials,catalysts if needed, and most other additives, including reinforcingmaterials and fillers such as glass in various forms including, forexample, fibers, flaked, or milled.

We have found that untreated reinforcing materials and fillers addedseparately from chloro and isocyanate silane to the liquid components ofa conventional RIM system display advantages similar to those disclosedfor adding pretreated filler materials as in Ser. No. 502,382 referredto above.

SUMMARY OF THE INVENTION

The invention is reaction injection molded (RIM) elastomer comprising acured reaction product of polyols of greater than about 1,500 molecularweight and/or primary or secondary amine terminated polyethers ofgreater than 1,500 molecular weight, a chain extender, a chloro and/orisocyanate silane coupling agent, untreated filler material, and anaromatic polyisocyanate. The invention is also a method of preparationof a RIM elastomer, as described above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The polyols useful in the process of this invention include polyetherpolyols, polyester diols, triols, tetrols, etc., having an equivalentweight of at least 500, and preferably at least 1,000 up to about 3,000.Those polyether polyols based on trihydric initiators of about 4,000molecular weight and above are especially preferred. The polyethers maybe prepared from ethylene oxide, propylene oxide, butylene oxide ormixtures of propylene oxide, butylene oxide and/or ethylene oxide. Inorder to achieve the rapid reaction rates which are normally requiredfor molding RIM polyurethane elastomers, it is preferable that thepolyol be capped with enough ethylene oxide to increase the reactionrate of the polyurethane mixture. Normally at least 50% primary hydroxylis preferred, although amounts of primary hydroxyl less than this areacceptable if the reaction rate is rapid enough to be useful inindustrial application. Other high molecular weight polyols which may beuseful in this invention are polyesters or hydroxyl terminated rubbers(such as hydroxyl terminated polybutadiene). Hydroxyl terminatedquasi-prepolymers of polyols and isocyanates are also useful in thisinvention.

Especially preferred are amine terminated polyethers including primaryand secondary amine terminated polyether polyols of greater than 1,500average molecular weight having from 2 to 6 functionality, preferablyfrom 2 to 3, and an amine equivalent weight from about 750 to about4,000. Mixtures of amine terminated polyethers may be used. In apreferred embodiment the amine terminated polyethers have an averagemolecular weight of at least 2,500. These materials may be made byvarious methods known in the art.

The amine terminated polyether resins useful in this invention, forexample, are polyether resins made from an appropriate initiator towhich lower alkylene oxides such as ethylene oxide, propylene oxide,butylene oxide or mixtures thereof are added with the resulting hydroxylterminated polyol then being aminated. When two or more oxides are used,they may be present as random mixtures or as blocks of one or the otherpolyether. In the amination step it is highly desirable that theterminal hydroxy groups in the polyol be essentially all secondaryhydroxyl groups for ease of amination. Normally, the amination step doesnot completely replace all of the hydroxyl groups. However, the majorityof hydroxyl groups are replaced by amine groups. Therefore, the amineterminated polyether resins useful in this invention have greater than50 percent of their active hydrogens in the form of amine hydrogens. Ifethylene oxide is used it is desirable to cap the hydroxyl terminatedpolyol with a small amount of higher alkylene oxide to ensure that theterminal hydroxyl groups are essentially all secondary hydroxyl groups.The polyols so prepared are then reductively aminated by prior arttechniques, for example, as outlined in U.S. Pat. No. 3,654,370,incorporated herein by reference.

In the practice of this invention, a single high molecular weight amineterminated polyether resin may be used. Also, mixtures of high molecularweight amine terminated polyols such as mixtures of di- andtrifunctional materials and/or different molecular weight or differentchemical composition materials may be used.

Also, mixtures of polyols and amine terminated polyethers are includedwithin the scope of my invention.

The chain extenders useful in the process of this invention arepreferably difunctional. Mixtures of difunctional and trifunctionalchain extenders are also useful in this invention. The chain extendersuseful in this invention include diols, (ethylene glycol and 1,4-butanediol, for example) amino alcohols, diamines or mixtures thereof.

The aromatic diamine chain extenders useful in this invention include,for example, 1-methyl-3,5-diethyl-2,4 diaminobenzene, 1-methyl-3,5diethyl-2-6 diaminobenzene (both of these materials are also calleddiethyltoluene diamine or DETDA), 1,3,5-triethyl-2,6 diaminobenzene,3,5,3',5'-tetraethyl-4,4" diaminodiphenylmethane and the like.Particularly preferred aromatic diamine chain extenders are1-methyl-3,5-diethyl-2,4 diaminobenzene or a mixture of this compoundwith 1-methyl-3,5-diethyl-2,6 diaminobenzene. It is within the scope ofthis invention to include some aliphatic chain extender materials asdescribed in U.S. Pat. Nos. 4,246,363 and 4,269,945.

Other chain extenders which find use in the method of this invention arelow molecular weight polyoxyalkylene polyamines which contain terminalamine groups and are represented by the formula ##STR1## wherein x+y+zhas a value of about 5.3. The average amine hydrogen equivalent weightis about 67 and the product is commercially available from TexacoChemical Company as JEFFAMINE® T-403. Another related polyoxypropylenepolyamine is represented by the formula ##STR2## wherein x has a valueof about 5.6 This product has an average amine hydrogen equivalentweight of about 100 and is commercially available from Texaco ChemicalCompany as JEFFAMINE D-400. The product having the same formula as abovewherein x has an average value of about 2.6 is also useful. This producthas an average amine hydrogen equivalent weight of about 57.5 and iscommercially available from Texaco Chemical Company as JEFFAMINE D-230.

Other chain extenders will be apparent to those skilled in the art andthe above recitation is not intended to be a limitation on the inventionclaimed herein.

A wide variety of aromatic polyisocyanates may be used here. Typicalaromatic polyisocyantes include p-phenylene diisocyanate, polymethylenepolyphenylisocyanate, 2,6-toluene diisocyanate, dianisidinediisocyanate, bitolylene diisocyanate, naphthalene-1,4-diisocyanate,bis(4-isocyanatophenyl)methane, bis(3-methyl-3-isocyanatophenyl)methane,bis(3-methyl-4-isocyanatophenyl)methane, and 4,4'-diphenylpropanediisocyanate.

Other aromatic polyisocyanates used in the practice of the invention aremethylene-bridged polyphenyl polyisocyanate mixtures which have afunctionality of from about 2 to about 4. These latter isocyanatecompounds are generally produced by the phosgenation of correspondingmethylene bridged polyphenyl polyamines, which are conventionallyproduced by the reaction of formaldehyde and primary aromatic amines,such as analine, in the presence of hydrochloric acid and/or otheracidic catalysts. Known processes for preparing polyamines andcorresponding methylene-bridged polyphenyl polyisocyanates therefrom aredescribed in the literature and in many patents, for example, U.S. Pat.Nos. 2,683,730; 2,950,263; 3,012,008; 3,344,162 and 3,362,979.

Usually methylene-bridged polyphenyl polyisocyanate mixtures containabout 20 to about 100 weight percent methylene diphenyldiisocyanateisomers, with the remainder being polymethylene polyphenyl diisocyanateshaving higher functionalities and higher molecular weights. Typical ofthese are polyphenyl polyisocyanate mixtures containing about 20 to 100weight percent methylene diphenyldiisocyanate isomers, of which 20 toabout 95 weight percent thereof is the 4,4'-isomer with the remainderbeing polymethylene polyphenyl polyisocyanates of higher molecularweight and functionality that have an average functionality of fromabout 2.1 to about 3.5. These isocyanate mixtures are known,commercially available materials and can be prepared by the processdescribed in U.S. Pat. No. 3,362,979, issued Jan. 9, 1968 to Floyd E.Bentley.

By far the most preferred aromatic polyisocyanate is methylenebis(4-phenylisocyanate) or MDI. Pure MDI, quasi-prepolymers of MDI,modified pure MDI, etc. Materials of this type may be used to preparesuitable RIM elastomers. Since pure MDI is a solid and, thus, ofteninconvenient to use, liquid products based on MDI are often used and areincluded in the scope of the terms MDI or methylenebis(4-phenylisocyanate) used herein. U.S. Pat. No. 3,394,164 is anexample of a liquid MDI product. More generally uretonimine modifiedpure MDI is included also. This product is made by heating puredistilled MDI in the presence of a catalyst. The liquid product is amixture of pure MDI and modified MDI: ##STR3## Examples of commercialmaterials of this type are Upjohn's ISONATE® 125M (pure MDI) and ISONATE143L ("liquid" MDI). Preferably the amount of isocyanates used is thestoichiometric amount based on all the ingredients in the formulation orgreater than the stoichiometric amount.

Of course, the term polyisocyanate also includes quasi-prepolymers ofpolyisocyanates with active hydrogen containing materials.

If needed, the following catalysts are useful. Catalysts such astertiary amines or an organic tin compound or other polyurethanecatalysts are used. The organic tin compound may suitably be a stannousor stannic compound such as a stannous salt of a carboxylic acid, atrialkyltin oxide, a dialkyltin dihalide, a dialkyltin oxide, etc.,wherein the organic groups of the organic portion of the tin compoundare hydrocarbon groups containing from 1 to 8 carbon atoms. For example,dibutyltin dilaurate, dibutyltin diacetate, diethyltin diacetate,dihexyltin diacetate, di-2-ethylhexyltin oxide, dioctyltin dioxide,stannous octoate, stannus oleate, etc., or a mixture thereof, may beused.

Tertiary amine catalysts include trialkylamines (e.g., trimethylamine,triethylamine), heterocyclic amines, such as N-alkylmorpholines (e.g.,N-methylmorpholine, N-ethylmorpholine, dimethyldiaminodiethylether,etc.), 1,4-dimethylpiperazine, triethylenediamine, etc., and aliphaticpolyamines such as N,N,N'N'-tetramethyl-1,3-butanediamine.

Other conventional formulation ingredients may be employed as neededsuch as; for example, foam stabilizers, also known as silicone oils oremulsifiers. The foam stabilizers may be an organic silane or siloxane.For example, compounds may be used having the formula:

    RSi[O-(R.sub.2 SiO).sub.n -(oxyalkylene).sub.m R].sub.3

wherein R is an alkyl group containing from 1 to 4 carbon atoms; n is aninteger of from 4 to 8; m is an integer of from 20 to 40; and theoxyalkylene groups are derived from propylene oxide and ethylene oxide.See, for example, U.S. Pat. No. 3,194,773.

Chloro and/or isocyanate silane coupling agents are useful in thisinvention. Exemplary of these materials are monomers of the formulaR-SiX₃, where R is the chloro or isocyanate group and X are hydrolizablegroups which are converted to silanol groups when hydrolized. Typicalexamples are:

    Cl(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 and NCO(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3

The chloro silane is preferred.

Other similar materials known to those skilled in the art are includedin the scope of this invention.

Reinforcing or filler materials useful in the practice of this inventionare, for example, materials such as fiberglass, milled glass, flakedglass, mica or Wollastonite. Especially useful is flaked glass.Untreated materials such as those above are preferred for thisinvention. Of course, reinforcing or filler materials which have beentreated with various sizing agents such as epoxy, amine or isocyanate,for example, can also be used so long as the chloro and/or isocyanatesilane coupling agent is also added separately. Pending application Ser.No. 502,382 filed June 8, 1983, claims RIM elastomers using epoxymodified filler materials.

Mold release agents useful for the method of this invention are internalmold release agents. The preferred mold release agent is Dow-CorningQ2-7119. This mold release agent is a dimethyl siloxane with organicacid groups manufactured by Dow-Corning Corporation.

Post curing of the elastomers of the invention is optional. Post curingwill improve some properties such as heat sag. Employment of postcuring, however, depends on the desired properties of the end product.

EXAMPLE 1

In this example, the following formulation was run in an AccuratioVR-100 machine and plaques of the composite RIM material were made:

    ______________________________________                                        B-component                                                                   JEFFAMINE ® T-5000  62.33  pbw                                            Diethyltoluenediamine (DETDA)                                                                         27.5   pbw                                            3-chloropropyltrimethoxy-silane                                                                       1.0    pbw                                            coupling agent                                                                OCF 1/64" flakeglass (unsized)*                                                                       43.1   pbw                                            A Component                                                                   Upjohn Code 205 Isocyanate                                                                            81.6   pbw                                            (a 2:1 by wt. quasi-prepolymer                                                of Isonate ® 143L and Thanol ®                                        SF-5505)                                                                      ______________________________________                                    

Plaques of this material had properties as are listed in Table 1. Whenexposed to 400° F. for one hour, test coupons to these plaques had nounacceptable surface blistering or distortion.

EXAMPLE 2

In this example the same formulation as in Example 1 was run in anAccuratio VR-100 RIM machine except that 1.0 pbw ofisocyanatopropyltrimethoxysilane was also added to the A-component. Theproperties of this material are listed in Table 1. When exposed to 400°F. for one hour, test coupons of these plaques had no unacceptablesurface blistering or distortion. This example illustrates the utilityof blends of coupling agents.

EXAMPLE 3

In this example, the same formulation as in Example 1 was run in theAccuration VR-100 RIM machine, except that instead of the 1.0 pbw of3-chloropropyltrimethoxy-silane coupling agent that was added to theB-component of Example 1, 1.0 pbw of isocyanatopropyltrimethoxy-silanecoupling agent was added to the A-component. The properties of thismaterial are listed in Table 1. When exposed to 400° F. for one hour,test coupons of these plaques had no unacceptable surface blistering ordistortion.

COMPARISON EXAMPLE A

The same formulation as in Example 1 was run in the Accuratio VR-100 RIMmachine except that no sizing was added to either the A- orB-components. This composite could not withstand 400° F. for one hourwithout blistering. In fact, gross blisters and surface distortions wereevident in this material when it was exposed to the 400° F. temperature.The properties of this material appear in Table 1.

                                      TABLE I                                     __________________________________________________________________________                                   Comparison                                     Material Properties                                                                       Example 1.sup.1                                                                     Example 2.sup.1                                                                      Example 3.sup.1                                                                     Example A.sup.1                                __________________________________________________________________________    Tensile strength, psi                                                                      3,000                                                                               2,886  2,710                                                                               2,600                                         Elongation, %                                                                             66    56     48    48                                             Flexural modulus, psi                                                         Measured at RT                                                                            182,000                                                                             186,000                                                                              182,000                                                                             168,000                                        158° F.                                                                            133,000                                                                             136,000                                                                              128,000                                                                             123,000                                        -20° F.                                                                            318,000                                                                             304,000                                                                              294,000                                                                             316,000                                        311° F.                                                                            110,000                                                                             114,000                                                                              115,000                                                                             124,000                                        Heat sag, mm                                                                  Measured at 250° F.                                                                 3     3      2    0.5                                            311° F.                                                                            7.5   7.55    7    5.8                                            400° F.                                                                            40    40     42    40.6                                           __________________________________________________________________________     .sup.1 Isocyanate index = 1.05; post cured one hour at 250° F.; 20     by weight flakeglass 1/64                                                

On inspection of Table I, several conclusions can be drawn:

1. The tensile strengths of composites containing coupling agents(Examples 1, 2, and 3) are higher than the tensile strength of thecomposite containing no coupling agent, Comparison Example A. This isespecially the case in Example 1.

2. The flexural modulus at room temperature is higher for the compositescontaining no coupling agents.

As described in the examples containing coupling agents (Examples 1, 2,and 3) no distortion or blistering was observed when these materialswere exposed to 400° F. for one hour, whereas gross distortion andblistering are observed at these conditions with the composite with nocoupling agent (Comparison Example A).

GLOSSARY OF TERMS AND MATERIALS

ISONATE® 143L--Carbodiimide modified liquid MDI; a product of the UpjohnCo.

JEFFAMINE® T-5000--Polypropylene oxide triamine of about 5,000 molecularweight; a product of Texaco Chemical Co.

DETDA--Diethyltoluene diamine; a product of Ethyl Corp.

THANOL® SF-5505--A 5500 molecular weight polyether triol containingapproxmately 80% primary hydroxy groups.

THANATE® L-55-0--Quasi-prepolymer--A quasi-prepolymer formed by reactingequal weight of ISONATE 143L and THANOL SF-5505; a product of TexacoChemical Co.

I claim:
 1. A reaction injection molded elastomer made by reacting in aclosed mold amine terminated polyethers of greater than 1,500 averagemolecular weight having greater than 50% of their active hydrogen in theform of amine hydrogens, a chain extender, a chloro silane couplingagent, untreated filler material, and an aromatic polyisocyanate.
 2. Anelastomer as in claim 1 wherein the filler material is glass based. 3.An elastomer as in claim 1 wherein the chain extender is diethyltoluenediamine.
 4. An elastomer as in claim 1 wherein the polyisocyanate is aquasi-prepolymer.
 5. A method for making a reaction injection moldedelastomer comprising reacting in a closed mold amine terminatedpolyethers greater than 2,500 average molecular weight having greaterthan 50% of their active hydrogen in the form of amine hydrogens, achain extender, a chloro silane coupling agent, untreated fillermaterial and an aromatic polyisocyanate.
 6. A method as in claim 5wherein the filler material is glass based.
 7. A method as in claim 5wherein the chain extender is diethyltoluene diamine.
 8. A method as inclaim 5 wherein the polyisocyanate is a quasi-prepolymer.
 9. A methodfor making a reaction injection molded elastomer comprising reacting ina closed mold amine terminated polyethers of at least 5,000 molecularweight and having a functionality of from about 2 to 3 having greaterthan 50% of their active hydrogen in the form of amine hydrogens, anamine terminated chain extender, a chloro silane coupling agent,untreated filler material and an aromatic polyisocynate.
 10. A method asin claim 9 wherein the chain extender is diethyltoluene diamine.
 11. Amethod as in claim 9 wherein the filler material is glass based.
 12. Areaction injection molded elastomer made by reacting in a closed mold apolyether polyol having an equivalent weight of at least 500, a chainextender, a chloro silane coupling agent, untreated filler material andan aromatic polyisocyanate.
 13. A method for making a reaction injectionmolded elastomer comprising reacting in a closed mold a polyether polyolhaving an equivalent weight of at least 500, a chain extender, a chlorosilane coupling agent, untreated filler material and an aromaticpolyisocyanate.
 14. A reaction injection molded elastomer made byreacting in a closed mold amine terminated polyethers of greater than1,500 average molecular weight having greater than 50% of their activehydrogen in the form of amine hydrogens, a chain extender, an isocyanatesilane coupling agent, untreated filler material, and an aromaticpolyisocyanate.
 15. A method for making a reaction injection moldedelastomer comprising reacting in a closed mold amine terminatedpolyethers greater than 1,500 average molecular weight having greaterthan 50% of their active hydrogen in the form of amine hydrogens, achain extender, an isocyanate silane coupling agent, untreated fillermaterial and an aromatic polyisocyanate.
 16. A reaction injection moldedelastomer made by reacting in a closed mold a polyether polyol having anequivalent weight of at least 500, a chain extender, an isocyanatesilane coupling agent, untreated filler material and an aromaticpolyisocyanate.
 17. A method for making a reaction injection moldedelastomer comprising reacting in a closed mold a polyether polyol havingan equivalent weight of at least 500, a chain extender, an isocyanatesilane coupling agent, untreated filler material and an aromaticpolyisocyanate.